FIG. 1 shows a conventional rotary atomizer 1, which can be used for example in a painting installation for painting motor vehicle body parts. The rotary atomizer 1 has a hollow turbine shaft 2, which is driven by a turbine and bears a bell cup 3 at its free end, the bell cup 3 being screw-fastened to the turbine shaft 2. A hollow paint tube 4 runs in the hollow turbine shaft 2, through which paint tube the paint to be applied is conveyed to the bell cup 3. A replaceable paint nozzle 5 is attached to the end face of the paint tube 4, which paint nozzle projects with its nozzle head axially through the bell cup 3 and directs the paint stream onto a distributor disc 6. Furthermore, the rotary atomizer 1 has a guide air ring 7, which has numerous guide air nozzles 8, which are distributed over the circumference and direct a guide air stream axially from behind e.g. onto a lateral surface 9 of the bell cup 3 in order to shape the spray jet output by the bell cup 3. The rotary atomizer 1 also allows a cleaning mode in that a rinsing agent is supplied instead of the paint via the paint tube 4 and the paint channel 10 running therein, which rinsing agent then cleans the inner surface of the bell cup 3 and the distributor disc 6.
A disadvantage of this known design is that the outer lateral surface 9 of the bell cup 3 cannot be cleaned with rinsing agent. On the other hand, a disadvantage of this design is that brief rinsing, during which the coating continues to be pushed as far as the paint nozzle 5 without interruption and only the bell cup 3 is briefly rinsed in between in order to prevent the coating drying on, is not possible.
FIG. 2 shows a likewise known conventional design of a bell cup 3 which partly corresponds to the design according to FIG. 1 described above, so reference is made to the above description, the same reference numerals being used for corresponding details, to avoid repetition. A similar design is also known from U.S. Pat. No. 6,341,734 B1.
A particular feature of this known design is that the paint nozzle 5 has, in addition to the continuous paint channel 10, a rinsing agent channel 11, which ends in a rinsing agent outlet in the front end face of the paint nozzle 5 and directs the rinsing agent essentially axially onto the distributor disc 6. The separation of the rinsing agent channel 11 from the paint channel 10 makes the above-described brief rinsing possible, as the coating can continue to be pushed as far as the paint nozzle 5 even during the rinsing process. A further particular feature of this known design is that the lateral surface 9 of the bell cup 3 can also be rinsed. To this end, a rinsing agent bore 12 branches off from the common rinsing agent channel 11, which bore conducts the rinsing agent through a further rinsing agent channel 13 in the bell cup 3 into an annular outer rinsing chamber of the bell cup 3, from where the rinsing agent then passes onto the outer lateral surface 9 of the bell cup 3. This external rinsing is also generally disclosed in EP 0 715 896 A2.
The disadvantage of this known design is the fact that when the rinsing agent pressure is too low, only the rear of the distributor disc 6 opposite the paint nozzle 5 is cleaned, while a distributor disc receptacle 15 contains dirt because the rinsing agent turbulences and the rebound of the rinsing agent from the distributor disc 6 are not sufficient to clean the distributor disc receptacle 15 completely with rinsing agent as well.
FIG. 3 likewise shows a known design of a bell cup 3 which partly corresponds to the conventional bell cups 3 described above, so reference is made to the above description, the same reference numerals being used for corresponding details, to avoid repetition.
A particular feature of this design is that the rinsing agent channel 11 opens into rinsing agent outlets which are axially offset to the rear in relation to the front end face of the paint nozzle 5.
A disadvantage of this design with axially set back rinsing agent outlets is however the insufficient cleaning of the central bore in the distributor disc receptacle 15 and the paint nozzle 5.
Finally, reference is also made to US 2008/0277496 A1. This document, while disclosing a wash passage for a rotary spraying head, also suffers from the disadvantage that an annular gap between a paint nozzle and a distributor disc receptacle surrounding it in an annular manner is not sufficiently rinsed during the washing process.
Accordingly, there is a need for a correspondingly improved paint nozzle.